An electronic smoking device, such as an electronic cigarette (e-cigarette), typically has a housing accommodating an electric power source (e.g., a single use or rechargeable battery, electrical plug, or other power source), and an electrically operable atomizer. The atomizer vaporizes or atomizes liquid supplied from a reservoir and provides vaporized or atomized liquid as an aerosol. Control electronics control the activation of the atomizer. In some electronic cigarettes, an airflow sensor is provided within the electronic smoking device, which detects a user puffing on the device (e.g., by sensing an under-pressure or an airflow pattern through the device). The airflow sensor indicates or signals the puff to the control electronics to power up the device and generate vapor. In other e-cigarettes, a switch is used to power up the e-cigarette to generate a puff of vapor.
Generally, the reservoir can include a porous media that can store the liquid, which can be drawn to the electrically operable atomizer, such as a heated coil. Upon contact between the liquid and the atomizer, the liquid can be atomized to form a vapor that is inhaled by the user. As liquid stored in the reservoir is used up, liquid that is stored within a close proximity to the atomizer can be wicked from the porous media. In contrast, liquid stored in the porous material at a further proximity to the atomizer may not be wicked to the atomizer because the liquid has to travel a further distance through the porous media. As a result, the amount of liquid media wicked to the atomizer may decrease even when additional liquid is stored in the porous media. This can cause a user of the e-cigarette to experience a drop-off in the “quality” of their experience, because less vapor is produced by the atomizer. This can give the user an impression that the porous media has been depleted of remaining liquid, causing the user to discard the porous media when some amount of liquid remains.